PMID- 34894562
OWN - NLM
STAT- MEDLINE
DCOM- 20220104
LR  - 20220104
IS  - 1873-3557 (Electronic)
IS  - 1386-1425 (Linking)
VI  - 268
DP  - 2022 Mar 5
TI  - Experimental and calculated infrared spectra of disubstituted naphthoquinones.
PG  - 120674
LID - S1386-1425(21)01251-8 [pii]
LID - 10.1016/j.saa.2021.120674 [doi]
AB  - In recent years there has been interest in incorporating substituted 
      1,4-naphthoquinones (NQs) into the A(1) binding site in photosystem I (PSI) 
      photosynthetic protein complexes. This interest in part stems from the 
      considerably altered bioenergetics of electron transfer that occur in PSI with 
      such substitutions. Time resolved FTIR studies of PSI complexes with 
      disubstituted NQs incorporated have and currently are being undertaken, and with 
      this in mind it is worth considering FTIR absorption spectra of these 
      disubstituted NQs in solution. Here we present FTIR absorbance spectra for 
      2-bromo-3-methyl-1,4-naphthoquinone (BrMeNQ), 
      2-chloromethyl-3-methyl-1,4-naphthoquinone (CMMeNQ) and 
      2-ethylthio-3-methyl-1,4-naphthoquinone (ETMeNQ) in tetrahydrofuran (THF). The 
      FTIR spectra of these di-substituted naphthoquinones (NQs) were compared to FTIR 
      spectra of 2-methyl-3-phytyl-1,4-naphthoquinone [phylloquinone (PhQ)], 
      2,3-dimethyl-1,4-naphthoquinone (DMNQ), and 2-methyl-1,4-naphthoquinone (2MNQ). 
      To aid in the assignment of bands in the experimental spectra, density functional 
      theory (DFT) based vibrational frequency calculations for all the substituted NQs 
      in solution were undertaken. The calculated and experimental spectra agree well. 
      By calculating normal mode potential energy distributions, unambiguous 
      quantitative band assignments were made. The calculated and experimental spectra 
      together make predictions about what may be observable in time resolved FTIR 
      difference spectra obtained using PSI with the different NQs incorporated. Time 
      resolved FTIR difference spectra are presented that support these predictions.
CI  - Copyright (c) 2021 Elsevier B.V. All rights reserved.
FAU - Agarwala, Neva
AU  - Agarwala N
AD  - Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, 
      USA.
FAU - Rohani, Leyla
AU  - Rohani L
AD  - Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, 
      USA.
FAU - Hastings, Gary
AU  - Hastings G
AD  - Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, 
      USA. Electronic address: ghastings@gsu.edu.
LA  - eng
PT  - Journal Article
DEP - 20211129
PL  - England
TA  - Spectrochim Acta A Mol Biomol Spectrosc
JT  - Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy
JID - 9602533
RN  - 0 (Naphthoquinones)
RN  - 0 (Photosystem I Protein Complex)
SB  - IM
MH  - Binding Sites
MH  - Electron Transport
MH  - *Naphthoquinones
MH  - Photosystem I Protein Complex
MH  - Spectroscopy, Fourier Transform Infrared
OTO - NOTNLM
OT  - Density functional theory
OT  - FTIR
OT  - Naphthoquinone
OT  - Phylloquinone
OT  - Vibrational frequency calculations
COIS- Declaration of Competing Interest The authors declare that they have no known 
      competing financial interests or personal relationships that could have appeared 
      to influence the work reported in this paper.
EDAT- 2021/12/12 06:00
MHDA- 2022/01/05 06:00
CRDT- 2021/12/11 20:12
PHST- 2021/07/25 00:00 [received]
PHST- 2021/10/21 00:00 [revised]
PHST- 2021/11/26 00:00 [accepted]
PHST- 2021/12/12 06:00 [pubmed]
PHST- 2022/01/05 06:00 [medline]
PHST- 2021/12/11 20:12 [entrez]
AID - S1386-1425(21)01251-8 [pii]
AID - 10.1016/j.saa.2021.120674 [doi]
PST - ppublish
SO  - Spectrochim Acta A Mol Biomol Spectrosc. 2022 Mar 5;268:120674. doi: 
      10.1016/j.saa.2021.120674. Epub 2021 Nov 29.